1. Field of the Invention
The present invention relates, in general, to needle-shaped bristles and methods of manufacturing the needle-shaped bristles and, more particularly, to a needle-shaped bristle, an end of which is tapered, and the other end of which is ground, and a method of manufacturing the needle-shaped bristle.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
Generally, a needle-shaped bristle is a bristle that is gradually reduced in diameter towards one end. Such a needle-shaped bristle exhibits superior ability to penetrate into gaps between teeth or between teeth and gums, and is soft. Thus, recently, needle-shaped bristles are used in most high-grade toothbrushes.
However, in the case of the needle-shaped bristle, because the end thereof is too soft, the cleaning ability is insufficient compared to a typical bristle. As an example of an attempt to overcome the above disadvantage, there has been a method proposed and used in which a bristle, only one end of which is tapered, is folded in half and set in a head part of a toothbrush such that a tapered end thereof is longer than an untapered end, as shown in FIG. 1. Several techniques related to this were proposed in Japan Utility Model No. Sho. 61-10495 and Korean Patent Registration No. 0464634, which was filed by the inventor of the present invention.
These techniques can mitigate the disadvantages of the needle-shaped bristle, but, because the edge of the cut end, which is not tapered, is sharp, it may injure the gums of a user. In an effort to overcome the above-mentioned problem, a method, in which the end of a bristle is tapered through a chemical treatment process and the other end thereof is also chemically treated for a short time to mitigate the sharpness before the bristle is set in a toothbrush, was proposed in Japan Patent Publication No. Heisei. 2002-192023.
However, this technique has relatively low production efficiency and is problematic in that a chemical treatment process, which creates poor working conditions, must be conducted two times. In addition, in the case of the chemical treatment process, there is a problem in that, if working conditions are changed even slightly, defective products are easily created. For these reasons, the above-mentioned method has not been widely used. In Korea, only the method shown in FIG. 1, in which a bristle, one end of which is tapered, and the other end of which is not tapered, is folded in half and is set in a toothbrush, has been used.